Transfusion Tissue - Thin walled cells - Between vascular tissue and endodermis - Mesophyll - Not divided into spongy and palisade layer - Found in fascicles (bundles) - 1st produced - Joined closely to one another within fascicle - As they grow → Spread out from other members of fascicle to produce fan-like spread of leaves - Fascicles - Can contain 2-5 leaves
Pine Reproduction - Produce 2 types of cones : - Seed Cones - Pollen Cones ** Often produced on same plant, but some species are DIOECIOUS - one plant producing seed cones and the other pollen cones. Pollen Cones - Composed of thin, papery scales attached to central cone axis - No bracts are involved - Smaller than seed cones - Consists of sporophylls - Sporophylls - Directly attached to cone axis - Supports sporangia - Sporangia - Has numerous microsporocytes - Microsporocytes - Undergo meiosis - Produce microspores - Microspores - Divide by mitosis - Form an immature male gametophyte - Pollen Grain - Male gametophyte - Released from pollen tubes into the air - Circulate with air currents - Some are carried to ovule of seed cone - Has 2 air bladders - Air Bladders - Provide buoyancy in air - Composed of 4 cells in the center area 1. Generative Cell - Produces 2 sperm cell 2. Tube Cell - Elongates to form pollen tube - Pollen Tube - Produced upon a pollen grain arriving in an ovule - Digests its way through the nucellus and the female gametophyte, into an archegonium and delivers sperm to the egg for fertilization 3. Body Cell 4. Body Cell - Gymnosperms and other seed plants produce ovules.
Ovules - Found in pairs - produced on surfaces of ovuliferous scales - Ovuliferous scales - Composed of bracts (which contain additional buds) - Attached to one central cone axis - Ovules are found at base - Base : where ovules attach to axis - Bracts - Branch off the central cone axis - Supports a bud that gives rise to sporophyll - Fuse with sporophylls to form ovuliferous scale - Bound by a integument - Integument - Protective wall of ovules - Houses the ff: - megasporangium - megaspore - female gametophyte - Eggs - After fertilized, integument hardens to form seed coat - Embryo develops within ovule - Entire structure is called SEED - Seed - Released when mature - Germinate when reach soil in suitable habitat - Micropyle - Opening of ovules in one end - Where pollen grains enter during pollination - Nucellus - Remnants of microsporangium - Where pollen grains rest Seed Cone - Female Pine cones - Large - Woody Process: e-cycle.html 1. Ovules are produced 2.
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- Summer '17
- Sperm, Flowering plant, Ovule, Pollen